Fish-based groups for ecological assessment in rivers: the importance of environmental drivers on taxonomic and functional traits of fish assemblages

Abstract

The use of river-types is of practical value, serving as groups for which assessment procedures can be developed and applied. An abiotic typology was set by the Portuguese Water Agency, mainly based on 6 major morphoclimatic regions. However, to be biologically meaningful, this typology should fit the distribution patterns of the biological quality elements communities proposed in Water Framework Directive under the lowest possible human pressure. This study aimed to identify and characterize fish-based geographical groups for continental Portugal and their environmental and geographical discriptors, using taxonomic and functional traits. Sampling took place between 2004 and 2006 during Spring. Fish fauna from 155 reference sites was analysed using a multivariate approach. Cluster Analysis on fish composition identified 10 fish-groups, expressing a clear correspondence to the river basin level, due to the restrict basin distribution of many species. Groups showed a wider aggregation in 4 regions with a larger geographical correspondence, statistically supported by Similarity Analysis, both on fish composition and mostly on fish metrics/guilds. Principal Components Analysis revealed major environmental drivers associated to fish-groups and fish-regions. Fish-groups were hierarchically grouped over major and local regions, expressing a large-scale response to a North-South environmental gradient defined by temperature, precipitation, mineralization and altitude, and a regional scale response mainly to drainage area and flow discharge. From North to South, fish-regions were related to the morphoclimatic regions. Results contributed to reduce redundance in abiotic river-types and set the final typology for Portuguese rivers, constituting a fundamental tool for planning and managing water resources.

Angling web forums as an additional tool for detection of new fish introductions: the first record ofPerca fluviatilisin continental Portugal

“…The anglers' preference for non-native game fishing, the availability of fishing guide services in the area and the influxes of fishermen may increase the introduction rate of non-native species in inland waters. The anglers' preference for non-native fish species may be related to the absence of native predatory or game fish species in the majority of the Portuguese river basins, particularly in the central and southern regions (Matono et al, 2012). In fact, native game fish species, namely the brown trout (Salmo trutta L.) and the Atlantic salmon (Salmo salar L.), are present mainly in the Northwest and in the mountain rivers of the Northern-Central region of Portugal (Cabral et al, 2005;Matono et al, 2012).…”

“…The anglers' preference for non-native fish species may be related to the absence of native predatory or game fish species in the majority of the Portuguese river basins, particularly in the central and southern regions (Matono et al, 2012). In fact, native game fish species, namely the brown trout (Salmo trutta L.) and the Atlantic salmon (Salmo salar L.), are present mainly in the Northwest and in the mountain rivers of the Northern-Central region of Portugal (Cabral et al, 2005;Matono et al, 2012). Additionally, since the introduction of the largemouth black bass (Micropterus salmoides) in the 1950s, by the National Authority for Inland Fisheries (Ribeiro et al, 2009), the importance and popularity of predatory fish, as well as the number of recreational anglers, has increased considerably in the last few decades (Santos et al, 2006).…”

Austropotamobius pallipes reduction vs. Procambarus clarkii spreading: Management implications

“…A. pallipes populations are quite isolated, being confined to small lotic waterbodies close to the upstream regions near the springs, at higher altitudes than sites occupied by P. clarkii. However, altitude may reflect the effect of several climatic factors such as temperature, precipitation or flow strength (Matono et al, 2012), even if it is more likely that cascades and natural barriers occur between a lowland site and a more elevated site than between two lowland sites (Rolls, 2011); altitude may also reflect the existence of barriers that at least up to now have prevented contact between native and alien crayfish. An important factor in determining the current distribution of native crayfish is water pollution, which we estimated through periphyton cover.…”